Grain Legumes and Green Manures for Soil Fertility in ... - cimmyt

tween factors tested in the study did not show any
significant effect for moisture content (Table 3). The
mean separations by LSDo.os (least significant differ~
ence) of depth (LSDoos = 0.4975) showed that there
was more moisture at 30-40 cm soil depth than
other depths (Figure 1).
The effect of time of incorporation on moisture content
approached significance (0.0677). The comparison
of means using LSDo.os (0.35) shows as well that
there is no significant difference in moisture content
between late (4.20%) and early (3.87%) incorporation
of green manure residues. Statistically, the difference
between times of incorporation of crop residues
was significant at 10%. The timp. of soil sampling
might have influenced the difference between
treatments on moisture conservation. Samples were
taken when the soil was too dry because of early
cessation of rain and late onset of rains for the following
season. However, the numerical difference
shows that late incorporation of green manure conserved
more moisture. This might be because in
early incorporation the soil is exposed to the sun,
and this increases evaporation, while in late incorporation
the plants continue to cover the soil, -Nhich
reduces evaporation.
Table 3. ANOVA table of moisture content measurements
Source OF Type III SS Mean Square FVal Pr > F
Treatment 5 2.01 0.40 0.36 0.8772
Depth 3 60.34 0.11 17.78 < 0.0001
Time 3.86 3.86 3.42 0.0677
Treatment" Depth 15 16.00 1.07 0.94 0.5204
Treatment "Time 5 3.16 0.63 0.56 0.7309
Depth"Time 3 3.04 1.01 0.90 0.4460
Treatment 15 8.42 0.56 0.50 0.9372
"Depth"Time
Residual 94 106.22 1.13
Total 143 210.74
There was a significant difference wi.thin treatments
between late and early incorporation of crop residues
(Figure 2) . . Late incorporation of cowpea, C.
juncea, C. grahamiana and maize conserved more
moisture than early incorporation, while incorporation
time of mucuna and soyabean residues did ~ot
show any significant ~ffect on moisture conservation.
A trend of means (not statistically significal'1t) of the
different treatments shows that soya bean had the
least moisture content, followed by C. grahamiana, C.
juncea, cowpea, maize and the highest to conserve
moisture was Mucuna pruriens (Figure 3). This
might be due to how these plants cover the ground.
Mucuna pruriens provides a good cover because of
its bushy habit that in return reduces evaporation
from the ground.
Addition of organic residues improves crop production
through moisture conservation and nutrient
supply to crops. Incorporated organic residues augment
the water retention capacity of the soil by improving
the structure and physical environment of
soil. The maximum benefits are achieved by good
timing of incorporation for growth of the' subsequent
crop. Consequently, there is need to conserve
soil moisture to avert moisture deficits at the time of
sowing, and provide much-needed nutrients at
early stages of plant growth.
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_ Early(a ll\owa nng)
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